CN112082584B - Optical fiber distributed physical quantity measuring method, device and system based on laser tuning control - Google Patents

Abstract

The application discloses an optical fiber distributed physical quantity measuring method based on laser tuning control, which is used for measuring physical quantity change of an object to be measured through an optical fiber sensor coupled to the object to be measured. The distributed feedback array laser is applied to the distributed physical quantity measuring device based on the optical frequency domain reflection technology, the method achieves the mode-hopping-free wavelength tuning range in a large range, and the spatial resolution and the measuring range of the distributed measuring method and the distributed measuring device are improved. The application also discloses a corresponding device and a corresponding system.

Description

Optical fiber distributed physical quantity measurement method, device and system based on laser tuning control

technical field

The invention belongs to the technical field of optical fiber sensing, and in particular relates to a high-resolution distributed physical quantity measurement method, device and system.

Background technique

The distributed physical quantity measurement based on the principle of optical frequency domain reflectometry is a technical means that can realize the distributed measurement of physical quantities. The related earlier documents include:

Distributed measurement of static strain in an optical fiber with multiple Bragg gratings at nominally equal wavelengths[J].Applied Optics,1998,37(10):1741-1746.

High-spatial-resolution distributed strain measurement in opticalfiber with Rayleigh scatter[J].Applied Optics,1998,37(10):1735-1740.

In the distributed physical quantity measurement system based on the principle of optical frequency domain reflection, tunable laser is used as the system light source, and the spatial resolution and range of the measurement system are limited by the modulation range of the output signal of the tunable laser. The spatial resolution of the system is numerically inversely proportional to the modulation range of the output signal of the tunable laser. The larger the tuning range, the higher the spatial resolution of the system. At the same time, the larger the tuning range is, the larger the measurement range of the effect of changes in physical quantities such as strain temperature and so on. It can be seen that in order to improve the spatial resolution of the system and the measurement range of physical quantities, it is necessary to improve the frequency sweep or tuning range of the tunable laser. In the prior art or device, an external cavity tunable laser or a semiconductor laser is usually used as a light source, but the external cavity tunable laser is expensive and prone to mode hopping. However, the frequency sweep range of semiconductor lasers is usually only tens of GHz (less than 1 nm), which cannot meet the spatial resolution requirements of distributed physical quantity measurement systems.

Distributed feedback array lasers (DFB array lasers) have been used in the field of optical communication in recent years, and have been widely used in optical transmission networks, optical interconnection, and other wavelength division multiplexing systems (References: [1] Ma Li, Zhu Hongliang, Liang Liang Song, Wang Baojun, Zhang Can, Zhao Lingjuan, Bian Jing, Chen Minghua. Monolithic integration of DFB laser array with MMI coupler and SOA. Optoelectronics. Laser, 2013, 24(03): 424-428. [2] Kobayashi, Go, et al.Narrow linewidth tunable lightsource integrated with distributed reflector laser array.Optical FiberCommunication Conference.Optical Society of America,2014.[3]Ni Y,Kong X,Gu X,et al.Packaging and testing of multi-wavelength DFB laser array using RECtechnology. Optics Communications, 2014, 312:123-126.). Compared with the traditional distributed feedback laser, the distributed feedback array laser is generally composed of a plurality of laser diodes with a certain interval in wavelength, a multi-mode interference coupler (MMI) and a semiconductor optical amplifier (SOA). Due to the existence of multiple laser diodes, the distributed feedback array laser can realize multiplexing of multiple channels.

SUMMARY OF THE INVENTION

The invention applies the distributed feedback array laser to the distributed sensing system based on the optical frequency domain reflection technology, and studies a high-resolution distributed physical quantity measurement method, device and system based on the distributed feedback array laser.

In order to achieve the purpose of the present application, the present application provides a fiber-optic distributed physical quantity measurement method based on laser tuning control, which is used to measure the physical quantity change of the object to be measured through an optical fiber sensor coupled to the object to be measured. The selected laser diodes in the distributed feedback array laser continuously cover all the selected laser diodes by changing their operating temperature so that adjacent selected laser diodes emit laser outputs with overlapping wavelength ranges. The main path interference light formed by the interference between the laser output with stable output power in the output wavelength range and the reflected light output by the optical fiber sensor for the laser output in the measurement state; converting the interference light into a main path interference light signal; The main path interference optical signal and the measurement state laser output wavelength monitoring signal containing the absolute wavelength information of the reference state laser output are synchronously collected in the measurement state including the physical quantity change, to obtain the measurement state main path interference optical signal and measurement state laser output wavelength monitoring signal; determine the splicing point in the collected measurement state main path interference optical signal according to the absolute wavelength information provided by the measurement state laser output wavelength monitoring signal; remove the collected measurement state main path interference The part other than the splicing point in the wavelength overlapping region in the optical signal forms the main path interference optical signal in the measured state after splicing; Calculate the change in the physical quantity.

Other embodiments of the present invention provide an optical fiber distributed physical quantity measurement device based on laser tuning control, which is used to measure the physical quantity change of the object to be measured through an optical fiber sensor coupled to the object to be measured. The device includes: a distributed feedback array laser, Selected laser diodes in a distributed feedback array laser configured to continuously cover the output wavelengths of all selected laser diodes by varying their operating temperature such that adjacent selected laser diodes emit laser outputs having overlapping wavelength ranges a range of output power stabilized laser outputs, a wavelength monitoring unit configured to receive the laser output to provide a wavelength monitoring signal containing absolute wavelength information of the laser output; a main path interferometer unit configured to receive the laser output and The reflected light of the optical fiber sensor makes the two interfere with each other to form a main path interference light signal; the acquisition unit is configured to synchronously collect the main path interference light signal and the wavelength monitoring signal in a measurement state including the physical quantity change Obtain the main path interference optical signal in the measurement state and the wavelength monitoring signal in the measurement state; the data processing unit is configured to determine the main path interference optical signal in the collected measurement state according to the absolute wavelength information provided by the received laser output signal in the measurement state. splicing point; removing the part other than the splicing point in the wavelength overlap region in the collected measurement state main path interference optical signal to form a spliced measurement state main path interference optical signal; and based on the post splicing measurement state main path interference optical signal The change of the physical quantity is calculated by the path interference optical signal and the main path interference optical signal in the reference state after splicing.

The present invention also provides an optical fiber distributed physical quantity measurement system based on the above device based on laser tuning control.

Beneficial effects of the present invention: The present invention applies the distributed feedback array laser to the distributed physical quantity measurement device based on the optical frequency domain reflection technology, realizes a large-scale wavelength tuning range without mode hopping, and improves the performance of the distributed measurement method and device. Spatial resolution and measurement range. The method and device have the advantages of simple control method and device, low cost, small volume, and favorable system integration.

Description of drawings

1 is a schematic structural diagram of a distributed feedback array laser according to an embodiment of the present application;

Fig. 2 is a kind of optical fiber distributed physical quantity measuring device based on laser tuning control according to an embodiment of the present application;

Fig. 3 is the hydrogen cyanide chamber absorption spectrum according to the embodiment of the application;

4 is a schematic diagram of determining a splice point according to an embodiment of the present application;

5 is an output signal of an FP standard device according to an embodiment of the present application;

6 is an output signal of a fiber optic interferometer according to an embodiment of the present application;

7 is an output signal of a fiber ring resonator according to an embodiment of the present application;

8 is a schematic diagram of the wavelength tuning range of each laser diode on a distributed feedback array laser under temperature tuning according to an embodiment of the present application; wherein,

In Fig. 1: 33 is a multi-mode interference coupler, 35 is a thermoelectric cooler, 36 is a thermistor, 37 is a substrate, and 38 is a plurality of laser diodes with a certain wavelength interval.

In Figure 2: 28 is the first laser diode pin, 29 is the second laser diode pin, 30 is the twelfth laser diode pin, 27 is the on-chip thermoelectric cooler pin, 1 is the main control module, 26 is the temperature Control module, 25 is a high-speed electrical switch, 24 is a current drive module, 2 is a distributed feedback array laser, 3 is a first fiber coupler, 4 is a second fiber coupler, 12 is a third fiber coupler, and 7 is the first fiber coupler. Four-fiber coupler, 23 is a time delay fiber, 20 is a wavelength monitoring device, 21 is an auxiliary interferometer, 22 is a main path interferometer, 19 is a collection device, 18 is a first photodetector, and 15 is a second photodetector , 10 is the third photodetector, 31 is the storage module, 32 is the data processing module, 13 is the first Faraday rotating mirror, 14 is the second Faraday rotating mirror, 6 is the sensing fiber, and 39 is the external tensile strain.

In Fig. 4, 70 is the splicing position of the output signal of the main path interferometer of the previous section, 71 is the splicing position of the output signal of the main path interferometer of the next section, 72 is the output signal output signal of the main path interferometer of the previous section, and 73 is the output light of the next section. Signal, 74 is the signal of the previous segment passing through the air chamber, 75 is the signal of the latter segment passing through the air chamber, and 77 is the main path interferometer output optical signal after interception and splicing.

In FIG. 8, 55 is the wavelength tuning range of the first laser diode, 57 is the wavelength tuning range of the second laser diode, 58 is the wavelength tuning range of the third laser diode, 58 is the wavelength tuning range of the tenth laser diode, and 59 is the wavelength tuning range of the tenth laser diode. The wavelength tuning range of the eleventh laser diode, 60 is the wavelength tuning range of the twelfth laser diode.

Detailed ways

FIG. 1 is a schematic structural diagram of a typical distributed feedback array laser. Usually, the distributed feedback array laser is composed of a piece of integrated multiple laser diodes 38 with different wavelengths and a multi-mode interference coupler 33 for beam combining. At the same time, the substrate 37 of the distributed feedback array laser has a A thermoelectric cooler 35 for heating or cooling controlled by current and a thermistor 36 whose resistance varies with temperature. Take Japan's FITEL company's D66 distributed feedback array laser as an example, 12 laser diodes with a wavelength interval of 3.5nm are integrated on a single chip (https://www.furukawa.co.jp/fitel/english/active/pdf /signal/ODC-7AH001H_FRL15TCWx-D66-xxxxx-D.pdf). The output wavelength of the distributed feedback array laser responds to both temperature and current. The usual usage is to use the thermoelectric cooler 35 to adjust the temperature of the laser array to achieve wavelength tuning, and the laser output wavelength has a low response sensitivity to the current, so the current is generally used for a small range of wavelength tuning or to control the output optical power. Without loss of generality, the following describes how to realize the measurement by using the distributed feedback array laser and its parameters as the light source of the high-speed and high-resolution distributed physical quantity measurement device.

In Fig. 1: 33 is a multi-mode interference coupler, 35 is a thermoelectric cooler, 36 is a thermistor, 37 is a substrate, and 38 is a plurality of laser diodes with a certain wavelength interval.

The invention applies the distributed feedback array laser to the distributed sensing system based on the optical frequency domain reflection technology, and studies a high-resolution distributed physical quantity measurement method and device based on the distributed feedback array laser. The high-resolution distributed physical quantity measurement method and device proposed in this patent will use a distributed feedback array laser as the system light source. Each laser diode in the distributed feedback array laser will realize the light source requirements of the distributed physical quantity measurement system through temperature tuning and spectral multiplexing.

Taking FIG. 2 as an example, a high-resolution distributed physical quantity measurement method and device based on a distributed feedback array laser is described. The distributed feedback array laser 2 controls the high-speed electrical switch 25 through the main control module 1 to switch different laser diodes, and the constant current generated by the current drive module is sequentially connected to the anodes of each pin of the distributed feedback array laser 2. The anode pins are shown in the figure 2 the first laser diode pin 28, the second laser diode pin 29, up to the twelfth laser diode pin 30. Under constant current, the laser outputs a constant power laser. The main control module 1 controls the temperature control module 26 to control the thermoelectric cooler 35 on the distributed feedback array laser 2 to change the laser temperature. The wavelength of the laser output light changes with the temperature of the laser. Usually this tuning factor is a certain value, such as 0.1nm per degree Celsius. When the temperature changes from 15 degrees to 55 degrees, the output light wavelength changes about 4nm. For the D66 distributed feedback array laser, the natural wavelength interval between adjacent laser diodes is 3.5nm. Therefore, for each laser diode, if the amount of wavelength changed by temperature tuning is greater than the natural wavelength interval, the wavelength overlap of each laser diode sweep frequency range can be achieved. Meanwhile, in the following embodiments, in order to achieve the maximum wavelength tuning range, all the laser diodes in the distributed feedback array laser 2 are wavelength tuned by temperature. However, if only a part of the laser diodes in the distributed feedback array laser 2 are wavelength tuned and the remaining part is discarded, it is also possible if the required wavelength range can be satisfied. At the same time, it is also defined that the output wavelength of the laser increases with the increase of temperature, and the output wavelength of the laser increases with the increase of the serial number of the laser diode inside the distributed feedback array laser.

The main control module 1 controls the current driving module 24 to generate a current signal of constant magnitude, and at the same time, switches to the No. 1 laser diode through the high-speed electrical switch 25 . The main control module 1 controls the temperature control module 26 to control the 35 thermoelectric cooler on the distributed feedback array laser 2 to change the laser temperature. The temperature control module 26 may be a chip MAX1978. At the same time, considering that the response speed of the laser output wavelength to temperature changes is low, the control signal of the temperature control module 26 can be directly a step signal. Experiments show that when the temperature control signal is a step current signal, the temperature rises from 15 degrees to 55 degrees It takes about 0.5 seconds to complete. The laser output wavelength increases monotonically with increasing temperature. The laser output from the laser enters the first fiber coupler 3 , where the laser is divided into three output beams and enters the wavelength monitoring device 20 , the auxiliary interferometer 21 and the main path interferometer 22 respectively. The wavelength monitoring device 20 includes a hydrogen cyanide molecular gas cell that can output a characteristic signal, and its absorption spectrum is shown in FIG. 4 , which is absorbed at a specific traceable wavelength position, and the light passing through the hydrogen cyanide molecular gas cell is detected by the first photoelectric detection. The detector 18 detects and photoelectrically converts it to be collected by a collection channel of the collection device 19 and transmitted to the storage module 31 . The acquisition device 19 may be a multi-channel oscilloscope or an acquisition card. At the same time, a part of the light is output to the auxiliary interferometer 21 through the other output port c of the first fiber coupler 3, and the auxiliary interferometer 21 may be the structure of the Michelson interferometer shown in FIG. The delay optical fiber 23 , the first Faraday rotating mirror 13 , the second Faraday rotating mirror 14 , and the second photodetector 15 are constituted. For the Michelson structure interferometer shown in the figure, the signal output by the interferometer during the laser tuning process is a sine signal, and the period of the sine is related to the swept wavelength range and the length of the delay fiber 23 . The longer the length of the delay fiber 23 is, the smaller the period of the sine is, and the smaller the wavelength range swept by each sine is. At the same time, the sinusoidal signal directly corresponds to the phase of the output signal of the light source, so the interferometer can track the wavelength or phase of the laser output by the tuned laser, which can be used for subsequent nonlinear correction. The sinusoidal signal output by the auxiliary interferometer 21 is collected by the collecting device 19 . The other output port d of the three-port optical fiber coupler 3 outputs light to the main path interferometer 22. The main path interferometer is also an optical path structure for completing measurement or sensing. Figure 2 shows a Mach-Zehnder structure fiber optic interferometer. , the second fiber coupler 4 splits a bundle of reference arms and is directly connected to the fourth fiber coupler 7, and the other is the measurement arm, which is output from the second fiber coupler 4 to the a port of the circulator 5. The characteristics of the circulator 5 are a in c out, c in b out. Therefore, the light entering from the a port of the circulator 5 enters the measurement sensing fiber 6, and the scattered or reflected signal on the measurement sensing fiber 6 returns to the circulator 5 and enters the b port of the circulator 5 and then enters the fourth Fiber coupler 7. After the two beams are combined in the fiber coupler 7 , they are detected by the third photodetector 10 and collected by the collecting device 19 . The three-way signals are collected by the collection device 19 and then transmitted to the storage module 31 and then to the data processing module 32 .

Next, the main control module 1 controls the high-speed electrical switch 25 to switch to the No. 2 laser diode, and the main control module 1 controls the temperature control module 26 to control the thermal cooling temperature thermoelectric cooler integrated on the distributed feedback array laser 2 to change the laser temperature. Other collection procedures are the same as those described in the previous paragraph. The three-way signals are collected by the collection device 19 and then transmitted to the storage module 31 and then to the data processing module 32 .

By analogy, the wavelength tuning process of each selected laser diode on the distributed feedback array laser is completed and the data is recorded. It is assumed here that as the temperature increases, the output wavelength of the laser increases. At the same time, as the serial number of the laser diode inside the distributed feedback array laser increases, the output wavelength of the laser increases. The recorded data is the data of each laser diode passing through each module of the sensing or measuring device when the driving current is constant and the output tuning laser is only used for temperature tuning. In order to obtain data in a wide range of wavelengths, it is necessary to splicing the data tuned by each laser diode, and use the spliced data as the input of distributed physical quantity demodulation, and then obtain the distributed physical quantity result.

The principle of distributed physical quantity measurement or sensing based on the principle of optical frequency domain reflectance is to use the different sizes of beat frequencies corresponding to different positions on the sensing or measuring fiber to perform micron-scale spatial positioning. Theoretically, the spatial resolution of two points on the fiber is Δz=c/2nΔF, where c is the speed of light in vacuum, n is the refractive index in the fiber, and ΔF is the optical frequency range swept by the tunable laser. Therefore, in order to reduce the value of the spatial resolution of the two points on the fiber, and to improve the spatial resolution, the tuning range should be expanded. At the same time, the distributed physical quantity measurement or sensing based on the principle of optical frequency domain reflection calculates the variation of the physical quantity through the offset of the spectrum. Therefore, the larger the tuning range, the larger the range of the distributed physical quantity.

In order to realize the distributed demodulation of physical quantities, it is necessary to first record the data in the reference state, and then record the data in the measurement state. The operations performed in these two processes are the same. The collected data is distinguished by the reference state and the measurement state. The reference state wavelength monitoring output signal, the reference state auxiliary interferometer output signal, the reference state main path interferometer output signal, and the measurement state wavelength monitoring output signal, the measurement state auxiliary interferometer output signal, the measurement state main path interferometer output signal are stored in the storage module 31 . The storage module 31 transmits the original data to the data processing module 32, and the data processing module 32 completes operations such as nonlinear correction, determination of the position of the splice point, and distributed physical quantity demodulation. The demodulation result and the splicing point position and other results can be stored in the storage module 31 .

In view of the fact that the distributed physical quantity measurement or sensing based on the principle of optical frequency domain reflectance is a relative measurement, the reference state signal needs to be determined first. This reference state is collected in the first state of the outside world and stored in the computer. In the memory, and the second external state described below represents the measurement state, relative to the first reference state, the sensing fiber may have the effect of physical quantity change. The following describes the high-resolution distributed physical quantity measurement or sensing process based on distributed feedback array lasers.

Step 1: In the first state of the outside world, set the driving current of the distributed feedback array laser to a certain value, so that the distributed feedback array laser has a laser output of stable power. Controlling multiple laser diodes with gradually increasing output wavelengths specified in the distributed feedback array laser to change their temperature in turn to obtain a wavelength-tuning laser output; each laser diode of the distributed feedback array laser performs frequency-sweeping laser output under a certain range of temperature tuning respectively As the light source of the distributed physical quantity measurement device, it is input into the distributed physical quantity measurement device, and the reference state signal output by the distributed physical quantity measurement device under the wavelength tuning of each laser diode is recorded, including: the reference state wavelength monitoring output signal, the reference state auxiliary interferometer output signal, the reference state main path interferometer output signal;

In order to ensure that the wavelength tuning of each laser diode through temperature tuning can achieve a wide range of wavelength-free coverage and facilitate the subsequent determination of the position of the wavelength splicing point, in the wavelength tuning, it should be ensured that the starting wavelength of each laser diode under the temperature tuning is less than The stop wavelength of a laser diode with a larger intrinsic wavelength value adjacent to the laser diode is temperature tuned so that the output signals of the adjacent wavelength laser diodes partially overlap in the spectrum. For the D66 distributed feedback array laser of Japan's FITEL company, 12 laser diodes are sequentially tuned by temperature, and the wavelength tuning range experienced by each laser diode is shown in Figure 8. The first three lasers and the last three lasers are omitted in Figure 8. An illustration of the wavelength range of a diode. It can be seen that the entire band is covered without gaps due to the discrete and inherent spacing in wavelength of the laser diodes themselves in the laser array, as well as the tuning of a larger wavelength range of a single laser diode by changing the temperature.

Step 2. In the second state of the outside world, repeat step 1. At this time, the recorded signal is the measurement state signal output by the distributed physical quantity measurement device under the wavelength tuning of each laser diode, including: the measurement state wavelength monitoring output signal, the measurement state signal Auxiliary interferometer output signal, measurement state main path interferometer output signal;

Step 3: Determine the reference state wavelength overlap position and the measurement state wavelength overlap position output by each laser diode according to the reference state wavelength monitoring output signal and the measurement state wavelength monitoring output signal, and output signals to the reference state main path interferometer respectively according to the positions, The output signal of the auxiliary interferometer in the reference state, the output signal of the main path interferometer in the measurement state and the output signal of the auxiliary interferometer in the measurement state are intercepted and spliced to obtain the output signal of the main path interferometer in the reference state after splicing, and the auxiliary interferometer in the reference state after splicing. output signal, the output signal of the main path interferometer in the measurement state after splicing, and the output signal of the main path interferometer in the measurement state after splicing;

Step 4: Use the output signal of the auxiliary interferometer in the reference state after splicing and the output signal of the auxiliary interferometer in the measurement state after splicing to perform nonlinear correction on the output signal of the reference state main path interferometer and the output signal of the main path interferometer in the measurement state, to obtain the final The output signal of the main path interferometer in the reference state and the output signal of the main path interferometer in the final measurement state;

Step 5: Distributed physical quantity calculation: the calculation includes performing fast Fourier transform on the main path interference optical signal in the reference state after splicing and the main path interference optical signal in the measurement state after splicing to obtain the splicing The distance domain signal of the main path interference optical signal in the post reference state and the main path interference optical signal in the measurement state after splicing, respectively, the main path interference optical signal in the reference state after splicing and the main path interference optical signal in the measurement state after splicing are respectively The distance domain signal of the moving window is used to select the spatial sensing unit at the same position on the distance domain, and the inverse Fourier transform is performed on the spatial sensing unit signal selected by the moving window to obtain the spatial sensing unit corresponding to the moving window. The reference state Rayleigh scattering spectral signal and the measured state Rayleigh scattering spectral signal corresponding to the unit; cross-correlation operation is performed on the two to obtain the position of the maximum value of the cross-correlation operation result, and the position of the maximum value corresponds to the The measured physical quantity changes on the spatial sensing unit of the position; by sliding the moving window on the distance domain signal, the spatial sensing units at different positions on the distance domain are selected to obtain the physical quantity changes at different positions on the optical fiber.

In addition, under the condition that the content and order of steps 1 and 2 remain unchanged, steps 3 and 4 can be adjusted as: Step 3, use the output signal of the auxiliary interferometer in the reference state to output the main path interferometer in the reference state The signal and the wavelength monitoring output signal in the reference state are nonlinearly corrected, and the output signal of the auxiliary interferometer in the measuring state is used to perform nonlinear correction on the output signal of the main circuit interferometer in the measuring state and the wavelength monitoring output signal in the measuring state, and the reference state wavelength monitoring output after correction is obtained. Signal, the wavelength monitoring output signal in the measured state after calibration, the wavelength monitoring output signal in the reference state after calibration, and the wavelength monitoring output signal in the measured state after calibration; Step 4, according to the wavelength monitoring output signal in the reference state after calibration and the wavelength monitoring output in the measured state after calibration The signal determines the wavelength overlap position of the reference state and the wavelength overlap position of the measurement state output by each laser diode. According to the position, the output signal of the main path interferometer in the reference state and the output signal of the main path interferometer in the measurement state after calibration are respectively intercepted and spliced to obtain the signal interception and splicing. The final reference state main path interferometer output signal and the final measurement state main path interferometer output signal. The output signal of the main channel interferometer in the final reference state and the output signal of the main channel interferometer in the final measurement state will be used to participate in the demodulation of distributed sensing information.

Due to the nonlinearity of laser wavelength tuning brought about by temperature tuning, that is, the output optical frequency does not increase linearly with time. At this time, if each output signal is sampled with a fixed sampling rate, the sampling points are not equal to the optical frequency interval. This effect Deteriorates the spatial resolution of the sensing or measurement system. The above-mentioned non-linear correction method for the output signal of the main path interferometer in the measurement state and the wavelength monitoring output signal in the measurement state by using the output signal of the auxiliary interferometer has several different implementation modes: the acquisition device 19 can be used to obtain the auxiliary interferometer. The signal of the instrument and the signals of other channels are synchronously collected with a fixed sampling rate, and then nonlinear correction is performed on the output signal of the main channel interferometer or the output signal of wavelength monitoring in the data processing module. The method is to perform Hilbert expansion on the output signal of the auxiliary interferometer, perform phase unwrapping, and then divide the phase into equal parts, such as equal division according to π radians, to obtain the corresponding sampling points, and then use these sampling points to analyze the main path interferometer. The output signal and the wavelength monitoring output signal are resampled, and the resampled main path interferometer output signal and the wavelength monitoring output signal are nonlinear corrected signals. In addition, there are non-uniform Fourier transforms, de-slope filters, PNC phase compensation, etc., which are implemented by post-software processing to correct nonlinearity. In addition, the sinusoidal signal output by the auxiliary interferometer can also be used as the clock of the acquisition device 19, and the clock can be used as the acquisition clock of the main path interferometer output signal and the wavelength monitoring output signal to collect the two paths. Considering the existing prior art, this part will not be repeated here. Related literature can be found (1. Ding Zhenyang, Proposition and verification of several methods to improve OFDR performance, 2013, Tianjin University. 2. Fan, X., Y. Koshikiya and F. Ito, Phase-noise-compensated optical frequency domain reflectometry with measurementrange 3. Swept-wavelength Interferometric Interrogation of Fiber Rayleigh Scatter for Distributed Sensing Applications 4. Song, J., et al., Long-Range High Spatial Resolution DistributedTemperature and Strain Sensing Based on Optical Frequency-DomainReflectometry. IEEE Photonics Journal, 2014.6(3):p.1-8.)

The sensing fiber 6 can be an ordinary single-mode fiber, or a sensing fiber with a weak reflection fiber grating array inscribed with the same center wavelength (Use of 3000 Bragg grating strain sensors distributed on foureight-meter optical fibers during static load tests of a composite structure.) , or a sensing fiber with enhanced Rayleigh scattering (Loranger, S., et al., Rayleigh scatterbased order of magnitude increase in distributed temperature and strainsensing by simple UV exposure of optical fibre. Scientific Reports, 2015.5: p.11177.) etc. .

Wherein, if the sensing fiber is composed of a weakly reflective fiber grating array with equally spaced isocenter wavelengths, the distributed physical quantity calculation process in step 5 is: the calculation includes: The distance domain of the main path interference optical signal in the reference state after the splicing and the main path interference optical signal in the measurement state after the splicing signal, use the window function to select the corresponding part of each fiber grating in the distance domain signal, respectively use inverse Fourier transform to convert the selected part to the optical frequency domain, and obtain the reference state signal and measurement state of each fiber grating respectively. The grating spectral signal under the signal; the envelope detection is performed on the grating spectral signal of the reference state signal and the measured state signal and the peak position is found, and the peak position of the grating spectral signal of the reference state signal and the measured state signal of each fiber grating The difference represents the size of the measured physical quantity on the grating at this position; if the sensing fiber is an optical fiber with Rayleigh scattering, since there is no signal with random distribution in the optical frequency domain and no single peak, its spectral offset can be Obtained by cross-correlation, the peak position of cross-correlation corresponds to the offset of the spectrum (refer to Cui J, Zhao S, Yang D, et al. Investigation of the interpolation method to improve the distributed strain measurement accuracy in optical frequencydomain reflectometry systems [J ]. Applied optics, 2018, 57(6):1424-1431.). In addition, other known mature methods can be used to solve the offset of the spectral signal with peaks, such as the maximum method, the energy center of gravity method, etc., see the relevant literature (Tosi, D., Review and Analysis of Peak Tracking Techniques for Fiber Bragg Grating Sensors. Sensors, 2017. 17(10): p. 2368.).

Whether cross-correlation or peak detection is used in the distributed physical quantity solution, the direct result is the offset of the spectrum, and the offset of the spectrum is the response function of the distributed physical quantity. Figure 2 represents the measured physical quantity, ie the distributed strain, with the stretch 39 only. But the distributed physical quantity can be strain, or temperature, or other physical quantities that can cause strain or temperature changes in the optical fiber. The difference between these physical quantities and the spectral offset generally differs by a coefficient (sensitivity) or, for more accuracy, conforms to the relationship of a polynomial function, or the coefficient value can be obtained through calibration experiments (refer to CuiJ, Zhao S, Yang D, et al. Investigation of the interpolation method to improve the distributed strain measurement accuracy in optical frequency domainreflectometry systems[J].Applied optics,2018,57(6):1424-1431.).

In order to determine a splicing position in the wavelength overlap region so as to intercept and splicing the output signals of the auxiliary interferometer and the main path interferometer to obtain a continuous output signal without overlap, it is necessary to adjust the wavelength of the laser diode tuning process under each temperature tuning. monitoring or tracing. The process of using the laser wavelength monitoring device to determine the splicing position of the output signal of the auxiliary interferometer and the output signal of the main path interferometer is described below.

The laser wavelength monitoring device 17 itself can be a device that directly measures the wavelength, such as a spectrometer or a wavelength meter, or it can be a gas molecular gas cell that can characterize wavelength characteristics or changes, a fiber grating with a known center wavelength, or a fiber interferometer or Fab Standard device for the Riporo structure. For a spectrometer or a wavelength meter, the reading is the laser wavelength. In this case, it is only necessary to select any point in the overlapping area. Preferably, a point in the middle of the overlapping area can be selected as the splicing position.

Figure 4 is used to illustrate the process of using the hydrogen cyanide chamber as the laser wavelength monitoring device to determine the position of the splicing point, and the process of intercepting and splicing the output signals of the two adjacent main path interferometers. Figure 4 is the characteristic spectral line of the hydrogen cyanide molecular gas cell. In the wavelength tuning of the input optical signal, the transmitted light of the hydrogen cyanide molecular gas cell has the absorption spectral line in Figure 4, which is used as the wavelength reference of the C band. In Fig. 4, 72 and 73 are the output signals of a certain pair of adjacent two-segment main path interferometers, and 74 and 75 are the signals output by the wavelength monitoring device collected synchronously (here is the transmission signal of the hydrogen cyanide chamber). For the hydrogen cyanide cell transmission signal, the first signal 74 passing through the gas cell has absorption peaks at the wavelength positions λ _k-1 and λ _k , and the latter signal 75 passing through the gas cell has absorption peaks at the wavelength positions λ _k and λ _k+. There is an absorption peak at ₁ . Therefore, λ _k can be used as the splicing wavelength position. The positions of the sampling points corresponding to the output signal of the former main path interferometer and the output signal of the latter main path corresponding to this position are 70 and 71 respectively. For the output signal 72 of the main path interferometer in the previous stage, the data behind the sampling point 70 is discarded, and for the output signal 73 of the main path interferometer in the subsequent stage, the data in front of the sampling point 71 is discarded. The newly obtained output signals of the two adjacent main-path interferometers are sequentially spliced to obtain a new main-path interferometer output signal 77 . Similar processing is performed on the whole waveband (for the D66 distributed feedback array laser of Japan FITEL Company, it can be 12 laser diodes), the continuous laser output signal of the whole waveband can be obtained. The splicing here refers to the rearrangement of each wavelength band into a continuous output optical signal according to the wavelength sequence.

The laser wavelength monitoring device can also be an FP standard or a fiber optic interferometer or a fiber ring resonator, and the fiber optic interferometer can be a typical Mach-Zehnder interferometer or a Michelson interferometer. Figure 7 shows the signal of the tuned optical signal passing through the FP standard. For the high-coherence FP standard, the output signal has a sharp comb-shaped periodic signal, and its optical frequency spacing is the free spectral range of the FP standard, and its cavity Length is related to refractive index. This output signal can be used as a wavelength reference (Deng, Z., et al., Frequency-scanning interferometry for depth mapping using the Fabry–Perot cavity as a reference with compensation for nonlinear opticalfrequency scanning. Optics Communications, 2020.455: p.124556.) . Figure 8 shows the signal of the tuned optical signal passing through the fiber interferometer. The period of the sinusoidal signal is related to the optical path difference between the two arms of the interferometer. The period of the sinusoidal signal determines the free spectral range of the interferometer, which is the optical frequency spacing represented by each sinusoid. After Hilbert expansion of the signal, the phase change of the optical signal can be obtained, so the output signal can also be used as a signal of wavelength tracing (Ahn, T. and D. Y. Kim, Analysis of nonlinear frequency sweep in high-speed tunable lasersources using a self-homodyne measurement and Hilbert transformation. 2007.46(13):p.2394.). The output signal of a typical fiber ring resonator has a signal similar to that of an FP standard, with a sharp peak signal, and its free spectral range is related to the internal fiber length (Gao, W., et al., Angular RandomWalk Improvement of Resonator Fiber Optic Gyro by Optimizing Modulation Frequency. IEEE Photonics Journal, 2019. 11(4): p. 1-13.). Using the FP standard, the output signal of the fiber interferometer or the fiber ring resonator is often used with the absolute wavelength reference to perform wavelength traceable optical frequency tracing, and then determine the wavelength splicing position in the tuning coincidence region.

It can be seen that the present invention utilizes the basis and wavelength tuning characteristics of a distributed feedback array laser to monolithically integrate multiple laser diodes, and utilizes temperature to achieve the tuning of each laser wavelength. Full-coverage continuous wavelength tuning on a feedback array laser across all bands. Compared with other semiconductor lasers such as a single distributed feedback laser, it effectively expands the frequency sweep range of the light source of the distributed physical quantity measurement or sensing system, thereby improving the spatial resolution of the system and improving the measurement range of physical quantities. At the same time, compared with wavelength tuning with current, temperature tuning can tune a wider range of wavelengths. Within the safe temperature of the laser, each laser diode in the distributed feedback array laser can achieve a larger wavelength range, which can be achieved with adjacent laser diodes. The sweeping frequency range with overlapping wavelengths makes multiple bands without blanks to form an overall large-range wavelength-tunable laser output.

In this application, the main path interference light signal refers to the signal provided by the main path interferometer unit or other units with the same or substantially the same function; the auxiliary interference light signal refers to the signal provided by the auxiliary path interferometer unit or other units with the same or substantially the same function The signal provided by the unit; the laser output wavelength monitoring signal or wavelength monitoring signal for short refers to the signal provided by the laser wavelength monitoring unit or other units with the same or substantially the same function.

The above are only preferred specific embodiments of the present invention, and these specific embodiments are based on different implementations under the overall concept of the present invention, and the protection scope of the present invention is not limited to this. Anyone familiar with the technical field Changes or substitutions that can be easily conceived by a skilled person within the technical scope disclosed by the present invention shall be covered within the protection scope of the present invention.

The method, device and system disclosed in the present invention can also be implemented by the following specific examples:

1. Optical fiber distributed physical quantity measurement method based on laser tuning control, which is used for optical fiber transmission coupled to the object to be measured.

The sensor measures the physical quantity change of the object to be measured, and is characterized in that the method comprises the following steps:

The selected laser diodes in the distributed feedback array laser are provided to continuously cover all of the selected laser diodes by changing their operating temperature so that adjacent selected laser diodes emit laser outputs having overlapping wavelength ranges. The main path interference light formed by the interference of the laser output with the stable output power of the output wavelength range and the reflected light output by the optical fiber sensor to the laser output in the measurement state;

converting the interference light into a main path interference light signal;

The main path interference optical signal and the measurement state laser output wavelength monitoring signal including the absolute wavelength information of the reference state laser output are synchronously collected in the measurement state including the physical quantity change, to obtain the measurement state main path interference optical signal and Measuring laser output wavelength monitoring signal;

Determine the splicing point in the collected measurement state main path interference optical signal according to the absolute wavelength information provided by the measurement state laser output wavelength monitoring signal;

Removing the part other than the splicing point in the wavelength overlapping region in the collected measurement state main path interference optical signal to form a spliced measurement state main path interference optical signal; and

The physical quantity change is calculated based on the main path interference optical signal in the measured state after splicing and the main path interference optical signal in the reference state after splicing.

2. The method according to example 1, characterized in that: the reference state main path interference optical signal after splicing is a pre-stored signal or obtained by the following methods:

Synchronously collect the main path interference optical signal and the reference state laser output wavelength monitoring signal containing the absolute wavelength information of the reference state laser output in the reference state not including the physical quantity change, to obtain the reference state main path interference optical signal and the reference state laser output wavelength monitoring signal;

Determine the splicing point in the collected reference state main path interference optical signal according to the absolute wavelength information provided by the reference state laser output wavelength monitoring signal;

A part other than the splicing point in the wavelength overlapping region in the collected reference state main path interference optical signal is removed to form a reference state main path interference optical signal after splicing.

3. The method according to example 1, further comprising:

providing reference state auxiliary interference light of the laser output of the distributed feedback array laser in the reference state; converting the reference state auxiliary interference light into a reference state auxiliary interference light signal; synchronously collecting the reference state main path an interference optical signal, the reference state laser outputs a wavelength monitoring signal and a reference state auxiliary interference optical signal; and the collected reference state main path interference optical signal is nonlinearly corrected with the collected reference state auxiliary interference optical signal; as well as

providing measurement state auxiliary interference light output by the laser output of the distributed feedback array laser in the measurement state; converting the measurement state auxiliary interference light into a measurement state auxiliary interference light signal; synchronously collecting the measurement state main path an interference light signal, the measurement state laser output wavelength monitoring signal and the measurement state auxiliary interference light signal; and the collected measurement state auxiliary interference light signal is used to perform nonlinear correction on the collected measurement state main path interference light signal.

4. The method according to example 1, further comprising:

providing reference state auxiliary interference light of the laser output of the distributed feedback array laser in the reference state; converting the reference state auxiliary interference light into a reference state auxiliary interference light signal; synchronously collecting the reference state main path interference light signal, the reference state laser output wavelength monitoring signal and the reference state auxiliary interference light signal; based on the absolute wavelength information provided by the collected reference laser output wavelength monitoring signal, the reference state auxiliary interference light signal is spliced, and used The spliced reference state auxiliary interference optical signal performs nonlinear correction on the spliced reference state main path interference optical signal; and

providing measurement state auxiliary interference light output by the laser output of the distributed feedback array laser in the measurement state; converting the measurement state auxiliary interference light into a measurement state auxiliary interference light signal; synchronously collecting the measurement state main path interference light signal, the laser output wavelength monitoring signal and the measurement state auxiliary interference light signal; based on the absolute wavelength information provided by the collected measurement state laser output wavelength monitoring signal, the measurement state auxiliary interference light signal is spliced, and the splicing is used The measurement state auxiliary interference optical signal performs nonlinear correction on the spliced measurement state main path interference optical signal.

5. The method according to any one of the above examples, characterized in that: the nonlinear correction comprises estimating the phase of the laser output monitoring signal according to the auxiliary interference light signal, and thereby adjusting the collected data. The interferometer signal and the collected laser output wavelength monitoring signal are subjected to nonlinear correction, such as resampling; or, an auxiliary interferometer is used in combination with an optoelectronic phase-locked loop to achieve nonlinear correction.

6. The method according to any one of the above examples, wherein the nonlinear correction is used to obtain output signals with equal optical frequency intervals.

7. The method according to any one of the above examples, further comprising:

providing reference state auxiliary interference light of the laser output of the distributed feedback array laser in the reference state not including the physical quantity change; converting the reference state auxiliary interference light into a reference state auxiliary interference light signal; collecting the reference and using the reference state auxiliary interference light as the clock for synchronously collecting the reference state main path interference light signal and the laser output wavelength monitoring signal; and

providing measurement state auxiliary interference light including the laser output of the distributed feedback array laser in the measurement state of the physical quantity change; converting the measurement state auxiliary interference light into a measurement state auxiliary interference light signal; collecting the measurement state an auxiliary interference light signal; and the measurement state auxiliary interference light signal is used as a clock for completing the synchronous acquisition of the measurement state main path interference light signal and the laser output wavelength monitoring signal.

8. The method of any one of the preceding examples, wherein changing the operating temperature of the distributed laser comprises making the starting wavelength of each selected laser diode under tuning of the operating temperature less than The stop wavelength of a laser diode with a larger wavelength value adjacent to the laser diode is tuned at the operating temperature so that the output laser light of the adjacent wavelength laser diodes partially overlaps in the spectrum.

9. The method according to any one of the preceding examples, wherein a constant drive current control signal is provided to all laser diodes in the distributed feedback array laser.

10. The method according to any one of the above examples, characterized in that: the calculating the physical quantity change comprises comparing the reference state main path interference light signal after splicing and the main path interference light in the measured state after splicing. The signals are respectively subjected to fast Fourier transform to obtain the distance domain signal of the main path interference optical signal in the reference state after splicing and the main path interference optical signal in the measurement state after splicing, and the main path interference optical signal in the reference state after splicing is respectively analyzed. and the distance domain signal of the main path interference optical signal in the measured state after the splicing, using the moving window to select the spatial sensing unit at the same position on the distance domain, and performing the Fourier inverse of the spatial sensing unit signal selected by the moving window. Transform to obtain the reference state Rayleigh scattering spectral signal and the measured state Rayleigh scattering spectral signal corresponding to the spatial sensing unit corresponding to the moving window; perform cross-correlation operation on the two to obtain the maximum value of the cross-correlation operation result. The position of the maximum value corresponds to the change of the measured physical quantity on the spatial sensing unit of this position; the spatial sensing unit of different positions on the distance domain is selected by sliding the moving window on the distance domain signal Then, the physical quantity changes at different positions on the optical fiber are obtained.

11. The method according to any one of the above examples, characterized in that: the wavelength of the laser output from the laser diode inside the distributed feedback array laser increases with the increase of the external operating temperature.

12. The method according to any one of the above examples, characterized in that: for a situation where a weakly reflective fiber grating array with isocenter wavelengths is used as the optical fiber sensor; the calculating the physical quantity change comprises: calculating the physical quantity change. After splicing, the main path interference optical signal in the reference state and the main path interference optical signal in the measurement state after splicing are respectively subjected to fast Fourier transform to obtain the main path interference optical signal in the reference state after splicing and the main path interference in the measurement state after splicing. For the distance domain signal of the optical signal, use the window function to select the corresponding part of each fiber grating in the distance domain signal, and use the inverse Fourier transform to convert the selected part to the optical frequency domain, respectively, to obtain the reference of each fiber grating. The grating spectral signal under the state signal and the measurement state signal; the envelope detection is performed on the grating spectral signal of the reference state signal and the measurement state signal, and the position of the peak is found, and the reference state signal and the measurement state signal of each fiber grating The difference between the peak positions of the grating spectral signal represents the size of the measured physical quantity on the grating at this position.

13. The method according to any one of the above examples, wherein the physical quantity includes strain, or temperature, or other physical quantities that cause strain or temperature changes in the optical fiber sensor.

14. An optical fiber distributed physical quantity measurement device based on laser tuning control, for measuring the physical quantity change of the object to be measured by a fiber optic sensor coupled to the object to be measured, it is characterized in that the device comprises:

A distributed feedback array laser configured to provide that selected laser diodes in the distributed feedback array laser continuously cover all selected laser diodes by changing their operating temperature such that adjacent selected laser diodes emit laser outputs having overlapping wavelength ranges The output power of the laser diode is stable in the output wavelength range of the laser output,

a wavelength monitoring unit configured to receive the laser output to provide a wavelength monitoring signal containing absolute wavelength information of the laser output;

a main path interferometer unit, configured to receive the laser output and the reflected light of the optical fiber sensor and cause the two to interfere to form a main path interference light signal;

a collection unit, configured to synchronously collect the main path interference optical signal and the wavelength monitoring signal in the measurement state including the physical quantity change to obtain the main path interference optical signal in the measurement state and the wavelength monitoring signal in the measurement state;

data processing unit, configured as

Determine the splicing point in the collected measurement state main path interference optical signal according to the absolute wavelength information provided by the received measurement state laser output signal; remove the wavelength overlap region in the collected measurement state main path interference optical signal The part other than the splicing point described in to form the main path interference optical signal in the measured state after splicing; and

The physical quantity change is calculated based on the main path interference optical signal in the measured state after splicing and the main path interference optical signal in the reference state after splicing.

15. The device according to Example 14, characterized in that: the corresponding reference state main path interference optical signal after splicing is pre-stored or obtained in real time in the following manner:

The acquisition unit is configured to synchronously acquire the main path interference optical signal and the wavelength monitoring signal in the reference state to form a reference state main path interference optical signal and a reference state wavelength monitoring signal;

The data processing unit is configured to determine the splice point in the collected reference state main path interference optical signal according to the absolute wavelength information provided by the received reference state laser output signal; remove the collected reference state main path Parts other than the splicing point in the overlapping wavelength region of the optical signal are interfered to form the main path interference optical signal in the reference state after splicing.

16. The device according to any one of the above examples, further comprising a storage unit for storing the data processing unit to obtain the signal splicing position, storing the distributed physical quantity solution result or directly storing the original acquisition signal so as to be offline later. deal with.

17. The device according to any one of the above examples, wherein the optical fiber sensor is configured on the measurement arm of the main path interferometer unit, and is an ordinary single-mode fiber, or is engraved with an isocenter wavelength. The weakly reflective fiber grating array fiber, or the fiber with enhanced Rayleigh scattering.

18. The apparatus of any one of the preceding examples, wherein the distributed feedback array laser is configured such that the starting wavelength of each selected laser diode at the operating temperature tuning is less than The stop wavelength of a laser diode with a larger wavelength value adjacent to the laser diode is tuned at the operating temperature so that the output signals of the adjacent wavelength laser diodes partially overlap in the spectrum.

19. The apparatus according to any one of the above examples, further comprising a temperature control unit configured to provide an operating temperature control signal to the distributed feedback array laser so that the selected laser diode outputs all The reference state laser output and the measurement state laser output.

20. The apparatus according to any one of the above examples, further comprising a drive current control unit configured to provide a constant drive current control signal to the laser diodes in the distributed feedback array laser so that each laser diode Operates at constant drive current.

21. The apparatus according to any one of the above examples, further comprising a laser diode selection unit: configured to switch among the selected laser diodes a laser diode that provides laser output.

22. The device according to any one of the above examples, wherein the laser diode selection unit is an electrical switch.

23. The apparatus according to any one of the above examples, further comprising an auxiliary interferometer unit configured to generate a reference state auxiliary interferometric optical signal based on the received reference state laser output and based on the received measurement The state laser output generates a measurement state auxiliary interference light signal.

24. The device according to any one of the above examples, wherein the acquisition unit is configured to acquire the reference state auxiliary interference light signal and the measurement state auxiliary interference light signal and collect the collected reference state The auxiliary interference light signal and the measurement state auxiliary interference light signal are used as the acquisition clock to synchronously collect the reference state interference light, the measurement state main path interference light signal, the reference state laser output monitoring signal and the measurement state laser output monitoring signal .

25. The device according to any one of the above examples, characterized in that: the reference state main path interference light signal, the reference state auxiliary interference light signal, and the reference state laser output signal are collected synchronously; The phase of the collected reference state laser output monitoring signal is estimated by the state auxiliary interference light signal, and the collected reference state main path interference light signal and the reference state laser output monitoring signal are thus nonlinearly corrected to make the reference state The state main path interference optical signal and the reference state laser output monitoring signal have equal optical frequency intervals; and

Simultaneously collect the main path interference light signal in the measurement state, the auxiliary interference light signal in the measurement state, and the laser output monitoring signal in the measurement state; estimate the difference between the collected measurement state laser output monitoring signal and the auxiliary interference light signal in the measurement state. phase, and thus perform nonlinear correction on the collected measurement state interference optical signal and the measurement state laser output monitoring signal, so that the measurement state main path interference optical signal and the measurement state laser output monitoring signal have equal Optical frequency interval.

26. The apparatus of any one of the preceding examples, wherein the nonlinear correction comprises resampling.

27. The device according to any one of the above examples, characterized in that: using the auxiliary interferometer in combination with an optoelectronic phase-locked loop realizes the control of the main path interferometer and the laser output between the reference state and all Nonlinear correction of the measurement state.

28. The device according to any one of the above examples, wherein the main path interferometer unit comprises a fiber optic interferometer having a Mach-Zehnder structure or a Michelson structure.

29. The device according to any one of the above examples, characterized in that: the auxiliary path interferometer unit comprises an optical fiber interferometer having a Mach-Zehnder structure or a Michelson structure.

30. The device according to any one of the above examples, characterized in that: the wavelength monitoring unit comprises a gas cell that outputs a characteristic signal or a fiber grating with a known center wavelength, or a spectrometer or a wavelength that can directly obtain a wavelength. meter, or fiber optic interferometer or FP standard or optical resonator, or a combination of the above.

31. The device according to any one of the above examples, wherein the distributed feedback array laser includes a plurality of laser diodes with fixed wavelength intervals and a multi-mode interference coupler, and different laser diodes can pass Electrical means to switch and laser output.

32. Optical fiber distributed physical quantity measurement system based on laser tuning control, to measure the physical quantity change of the object to be measured, it is characterized in that, this system comprises:

an optical fiber sensor, coupled to the object to be measured;

A distributed feedback array laser configured to provide that selected laser diodes in the distributed feedback array laser continuously cover all selected laser diodes by changing their operating temperature such that adjacent selected laser diodes emit laser outputs having overlapping wavelength ranges The output power of the laser diode is stable in the output wavelength range of the laser output,

a wavelength monitoring unit configured to receive the laser output to provide a wavelength monitoring signal containing absolute wavelength information of the laser output;

a main path interferometer unit, configured to receive the laser output and the reflected light of the optical fiber sensor and cause the two to interfere to form a main path interference light signal;

a collection unit, configured to synchronously collect the main path interference optical signal and the wavelength monitoring signal in the measurement state including the physical quantity change to obtain the main path interference optical signal in the measurement state and the wavelength monitoring signal in the measurement state;

data processing unit, configured as

Determine the splicing point in the collected measurement state main path interference optical signal according to the absolute wavelength information provided by the received measurement state laser output signal; remove the wavelength overlap region in the collected measurement state main path interference optical signal The part other than the splicing point described in to form the main path interference optical signal in the measured state after splicing; and

The physical quantity change is calculated based on the main-path interference optical signal in the post-splicing measurement state and the main-path interfering optical signal in the post-splicing reference state.

33. The device according to example 32, wherein: the corresponding reference state main path interference optical signal after splicing is pre-stored or obtained in real time in the following manner:

The acquisition unit is configured to synchronously acquire the main path interference optical signal and the wavelength monitoring signal in the reference state to form a reference state main path interference optical signal and a reference state wavelength monitoring signal;

The data processing unit is configured to determine the splice point in the collected reference state main path interference optical signal according to the absolute wavelength information provided by the received reference state laser output signal; remove the collected reference state main path Parts other than the splicing point in the overlapping wavelength region of the optical signal are interfered to form the main path interference optical signal in the reference state after splicing.

34. The system according to any one of the above examples, further comprising a storage unit for storing the data processing unit to obtain the signal splicing position, storing the distributed physical quantity solution result or directly storing the original acquisition signal for later offline. deal with.

35. The system according to any one of the above examples, wherein the optical fiber sensor is configured on the measurement arm of the main path interferometer unit, and is an ordinary single-mode optical fiber, or is written with an isocenter wavelength. Fibers of weakly reflective fiber grating arrays, or fibers with enhanced Rayleigh scattering.

36. The system of any one of the preceding examples, wherein the distributed feedback array laser is configured such that the starting wavelength of each selected laser diode at the operating temperature tuning is less than The stop wavelength of a laser diode with a larger wavelength value adjacent to the laser diode is tuned at the operating temperature so that the output signals of the adjacent wavelength laser diodes partially overlap in the spectrum.

37. The system of any one of the preceding examples, further comprising a temperature control unit configured to provide an operating temperature control signal to the distributed feedback array laser to cause the selected laser diodes to output all of them. The reference state laser output and the measurement state laser output.

38. The system according to any one of the preceding examples, further comprising a drive current control unit configured to provide a constant drive current control signal to the laser diodes in the distributed feedback array laser so that each laser diode Operates at constant drive current.

39. The system of any one of the preceding examples, further comprising a laser diode selection unit: configured to switch among the selected laser diodes a laser diode that provides laser output.

40. The system of any one of the preceding examples, wherein the laser diode selection unit is an electrical switch.

41. The system of any one of the preceding examples, further comprising an auxiliary interferometer unit configured to generate a reference state auxiliary interferometric optical signal based on the received reference state laser output and based on the received measurement The state laser output generates a measurement state auxiliary interference light signal.

42. The system according to any one of the above examples, wherein the acquisition unit is configured to acquire the reference state auxiliary interference light signal and the measurement state auxiliary interference light signal and collect the collected reference state The auxiliary interference light signal and the measurement state auxiliary interference light signal are used as the acquisition clock to synchronously collect the reference state interference light, the measurement state main path interference light signal, the reference state laser output monitoring signal and the measurement state laser output monitoring signal .

43. The system according to any one of the above examples, characterized in that: the reference state main path interference light signal, the reference state auxiliary interference light signal, and the reference state laser output signal are collected synchronously; The phase of the collected reference state laser output monitoring signal is estimated by the state auxiliary interference light signal, and the collected reference state main path interference light signal and the reference state laser output monitoring signal are thus nonlinearly corrected to make the reference state The state main path interference optical signal and the reference state laser output monitoring signal have equal optical frequency intervals; and

Simultaneously collect the main path interference light signal in the measurement state, the auxiliary interference light signal in the measurement state, and the laser output monitoring signal in the measurement state; estimate the difference between the collected measurement state laser output monitoring signal and the auxiliary interference light signal in the measurement state. phase, and thus perform nonlinear correction on the collected measurement state main path interference optical signal and the measurement state laser output monitoring signal, so that the measurement state main path interference optical signal and the measurement state laser output monitoring signal With equal optical frequency interval.

44. The system of any preceding example, wherein the nonlinear correction includes resampling.

45. The system according to any one of the above examples, characterized in that: using the auxiliary interferometer in combination with an optoelectronic phase-locked loop realizes the control of the main path interferometer and the laser output in the reference state and all Nonlinear correction of the measurement state.

46. The system according to any one of the above examples, wherein the main path interferometer unit comprises a fiber optic interferometer having a Mach-Zehnder structure or a Michelson structure.

47. The system according to any one of the above examples, wherein the auxiliary path interferometer unit comprises a fiber optic interferometer having a Mach-Zehnder structure or a Michelson structure.

48. The system according to any one of the above examples, characterized in that: the wavelength monitoring unit includes a gas cell that outputs a characteristic signal or a fiber grating with a known center wavelength, or a spectrometer or a wavelength that can directly obtain a wavelength. meter, or fiber optic interferometer or FP standard or optical resonator, or a combination of the above.

49. The system according to any one of the above examples, wherein the distributed feedback array laser comprises a plurality of laser diodes with fixed wavelength intervals and a multi-mode interference coupler, and different laser diodes can pass Electrical means to switch and laser output.

Claims (49)

1. An optical fiber distributed physical quantity measuring method based on laser tuning control, which is used for measuring physical quantity change of an object to be measured through an optical fiber sensor coupled to the object to be measured, and is characterized by comprising the following steps:

providing main path interference light formed by interference of reflected light from the fiber optic sensor for the measurement state laser output that is stable in output power continuously covering all of the selected laser diode's output wavelength range by varying its operating temperature such that it emits laser output having an overlapping wavelength range with adjacent selected laser diodes;

converting the main path interference light into a main path interference light signal;

synchronously acquiring the main path interference optical signal and a measurement state laser output wavelength monitoring signal containing absolute wavelength information output by the measurement state laser in a measurement state comprising the physical quantity change to obtain a measurement state main path interference optical signal and a measurement state laser output wavelength monitoring signal;

determining splicing points in the acquired main path interference optical signals in the measurement state according to absolute wavelength information provided by the laser output wavelength monitoring signals in the measurement state;

removing the part except the splicing point in the wavelength overlapping region in the acquired main path interference optical signal in the measurement state to form a spliced main path interference optical signal in the measurement state; and

and calculating the physical quantity change based on the spliced measuring state main path interference optical signal and the spliced reference state main path interference optical signal.

2. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 1, wherein: the spliced reference state main path interference optical signal is a pre-stored signal or is obtained by the following method:

synchronously acquiring the main path interference optical signal and a reference state laser output wavelength monitoring signal containing absolute wavelength information output by the reference state laser under a reference state without the physical quantity change to obtain a reference state main path interference optical signal and a reference state laser output wavelength monitoring signal;

determining splicing points in the collected reference state main path interference optical signals according to absolute wavelength information provided by the reference state laser output wavelength monitoring signals;

and removing the part except the splicing point in the wavelength overlapping region in the acquired reference state main path interference optical signal to form a spliced reference state main path interference optical signal.

3. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 2, wherein: further comprising reference state assist light providing the laser output of the distributed feedback array laser in the reference state; converting the reference state auxiliary interference light into a reference state auxiliary interference light signal; synchronously acquiring the reference state main path interference optical signal, wherein the reference state laser outputs a wavelength monitoring signal and a reference state auxiliary interference optical signal; carrying out nonlinear correction on the acquired reference state main path interference optical signal by using the acquired reference state auxiliary interference optical signal; and providing measurement state assist interference light of the laser output of the distributed feedback array laser in the measurement state; converting the measurement state auxiliary interference light into a measurement state auxiliary interference light signal; synchronously acquiring the main path interference optical signal in the measurement state, and outputting a wavelength monitoring signal and an auxiliary interference optical signal in the measurement state by the laser in the measurement state; and carrying out nonlinear correction on the acquired main path interference optical signal in the measurement state by using the acquired auxiliary interference optical signal in the measurement state.

4. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 2, wherein: further comprising reference state assist light providing the laser output of the distributed feedback array laser in the reference state; converting the reference state auxiliary interference light into a reference state auxiliary interference light signal; synchronously acquiring the reference state main path interference optical signal, wherein the reference state laser outputs a wavelength monitoring signal and a reference state auxiliary interference optical signal; splicing the reference state auxiliary interference optical signal based on absolute wavelength information provided by the collected reference state laser output wavelength monitoring signal, and carrying out nonlinear correction on the spliced reference state main path interference optical signal by using the spliced reference state auxiliary interference optical signal; and providing measurement state assist interference light of the laser output of the distributed feedback array laser in the measurement state; converting the measurement state auxiliary interference light into a measurement state auxiliary interference light signal; synchronously acquiring the main path interference optical signal in the measurement state, and outputting a wavelength monitoring signal and an auxiliary interference optical signal in the measurement state by the laser in the measurement state; splicing the measurement state auxiliary interference optical signal based on absolute wavelength information provided by the collected measurement state laser output wavelength monitoring signal, and carrying out nonlinear correction on the spliced measurement state main path interference optical signal by using the spliced measurement state auxiliary interference optical signal.

5. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 3 or 4, wherein: the nonlinear correction comprises estimating the phase of the laser output wavelength monitoring signal according to the auxiliary interference optical signal, and thus carrying out nonlinear correction on the collected interferometer signal and the collected laser output wavelength monitoring signal; alternatively, an auxiliary interferometer is used in combination with an electro-optic phase-locked loop to achieve non-linear correction.

6. The fiber distributed physical quantity measurement method based on laser tuning control of claim 5, wherein: the non-linear correction is used to obtain an output signal at equal optical frequency intervals.

7. The optical fiber distributed physical quantity measuring method based on laser tuning control according to claim 3 or 4, characterized in that: further comprising providing reference state assist interference light of the laser output of the distributed feedback array laser in a reference state that does not include the physical quantity variation; converting the reference state auxiliary interference light into a reference state auxiliary interference light signal; collecting the reference state auxiliary interference optical signal; and using the reference state auxiliary interference light as a clock for synchronously acquiring the reference state main path interference light signal and the laser output wavelength monitoring signal; and providing measurement state assist interference light comprising the laser output of the distributed feedback array laser in a measurement state of the physical quantity change; converting the measurement state auxiliary interference light into a measurement state auxiliary interference light signal; collecting the measurement state auxiliary interference optical signal; and using the measurement state auxiliary interference optical signal as a clock for synchronously acquiring the measurement state main path interference optical signal and the laser output wavelength monitoring signal.

8. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 1, wherein: changing the operating temperature of the distributed feedback array laser includes causing the starting wavelength of each of the selected laser diodes tuned at the operating temperature to be less than the ending wavelength of the laser diode having the larger wavelength value adjacent to that laser diode tuned at the operating temperature such that the output lasers of the adjacent wavelength laser diodes partially overlap spectrally.

9. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 1, wherein: providing a constant drive current control signal to all laser diodes in the distributed feedback array laser.

10. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 1, wherein: the calculating the physical quantity change comprises performing fast fourier transform on the spliced reference state main path interference optical signal and the spliced measurement state main path interference optical signal respectively to obtain distance domain signals of the spliced reference state main path interference optical signal and the spliced measurement state main path interference optical signal, selecting a space sensing unit by using the same position of a moving window on a distance domain for the distance domain signals of the spliced reference state main path interference optical signal and the spliced measurement state main path interference optical signal respectively, and performing inverse fourier transform on the space sensing unit signals selected by the moving window to obtain reference state rayleigh scattering spectrum signals and measurement state rayleigh scattering spectrum signals corresponding to the space sensing units corresponding to the moving window; performing cross-correlation operation on the two to obtain the position of the maximum value of the cross-correlation operation result, wherein the position of the maximum value corresponds to the measured physical quantity change on the space sensing unit at the position; and selecting the space sensing units at different positions on the distance domain by sliding the moving window on the distance domain signal so as to obtain the physical quantity change at different positions on the optical fiber.

11. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 1, wherein: the wavelength of the output laser of the laser diode in the distributed feedback array laser increases along with the increase of the external working temperature.

12. The fiber distributed physical quantity measurement method based on laser tuning control according to claim 1, wherein: for the case of a weakly reflecting fiber grating array with an isocentric wavelength as the fiber sensor; the resolving the physical quantity change includes: fast Fourier transform is respectively carried out on the spliced reference state main path interference optical signal and the spliced measurement state main path interference optical signal to obtain a distance domain signal of the spliced reference state main path interference optical signal and the spliced measurement state main path interference optical signal, a window function is used for selecting a part corresponding to each fiber bragg grating in the distance domain signal, the selected part is converted into an optical frequency domain by using inverse Fourier transform respectively, and a reference state signal of each fiber bragg grating and a grating spectrum signal under the measurement state signal are respectively obtained; and carrying out envelope detection on the grating spectrum signals of the reference state signal and the measurement state signal and finding out the position of a peak value, wherein the difference value of the peak value positions of the grating spectrum signals of the reference state signal and the measurement state signal of each fiber grating represents the physical quantity of the object to be measured on the grating at the position.

13. The laser tuning control-based optical fiber distributed physical quantity measurement method according to claim 1, wherein: the physical quantity includes strain or temperature, or other physical quantity that causes strain or temperature change of the optical fiber sensor.

14. An optical fiber distributed physical quantity measuring device based on laser tuning control, which is used for measuring the physical quantity change of an object to be measured through an optical fiber sensor coupled to the object to be measured, and is characterized in that the device comprises: a distributed feedback array laser configured such that selected ones of the distributed feedback array lasers provide output power-stabilized laser output that continuously covers the output wavelength range of all of the selected laser diodes by changing their operating temperatures such that they emit laser output having overlapping wavelength ranges with adjacent ones of the selected laser diodes; a wavelength monitoring unit configured to receive the laser output to provide a wavelength monitoring signal containing absolute wavelength information of the laser output; a main path interferometer unit configured to receive the laser output and reflected light of the optical fiber sensor and cause the two to interfere to form a main path interference optical signal; the acquisition unit is configured to synchronously acquire the main path interference optical signal and the wavelength monitoring signal in a measurement state including the physical quantity change to obtain a main path interference optical signal and a measurement state wavelength monitoring signal in the measurement state; the data processing unit is configured to determine splicing points in the acquired main path interference optical signal in the measurement state according to the received absolute wavelength information provided by the wavelength monitoring signal in the measurement state; removing the part except the splicing point in the wavelength overlapping region in the collected measurement state main path interference optical signal to form a spliced measurement state main path interference optical signal; and calculating the physical quantity change based on the spliced measurement state main path interference optical signal and the spliced reference state main path interference optical signal.

15. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the spliced reference state main path interference optical signal is pre-stored or obtained in real time in the following mode: the acquisition unit is configured to synchronously acquire the main-state interference optical signal and the wavelength monitoring signal in a reference state to form a reference-state main-state interference optical signal and a reference-state wavelength monitoring signal; the data processing unit is configured to determine a splicing point in the acquired reference state main path interference optical signal according to absolute wavelength information provided by the received reference state wavelength monitoring signal; and removing the part except the splicing point in the wavelength overlapping region in the collected reference state main path interference optical signal to form a spliced reference state main path interference optical signal.

16. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the device also comprises a storage unit which is used for storing the signal splicing position obtained by the data processing unit, storing the distributed physical quantity resolving result or directly storing the original acquisition signal so as to facilitate later off-line processing.

17. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the optical fiber sensor is configured on the measuring arm of the main path interferometer unit, and is a common single mode optical fiber, or an optical fiber with a writing of a weak reflection optical fiber grating array with an isocentric wavelength, or an optical fiber with enhanced Rayleigh scattering.

18. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the distributed feedback array laser is configured to: each of the selected laser diodes has a starting wavelength tuned at the operating temperature that is less than an ending wavelength of a laser diode adjacent to the laser diode having a larger wavelength value tuned at the operating temperature such that output signals of adjacent wavelength laser diodes partially overlap spectrally.

19. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: also included is a temperature control unit configured to provide an operating temperature control signal to the distributed feedback array laser to cause the selected laser diode to output the reference state laser output and the measurement state laser output.

20. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the laser driver further comprises a drive current control unit configured to provide a constant drive current control signal to the laser diodes in the distributed feedback array laser such that each laser diode operates at a constant drive current.

21. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the method also comprises a laser diode selection unit: configured to switch a laser diode providing a laser output among the selected laser diodes.

22. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 21, wherein: the selected unit of the laser diode is an electrical switch.

23. The fiber distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: further comprising an auxiliary interferometer unit configured to generate a reference state auxiliary interference light signal based on the received reference state laser output and to generate a measurement state auxiliary interference light signal based on the received measurement state laser output.

24. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 23, wherein: the acquisition unit is configured to acquire the reference state auxiliary interference optical signal and the measurement state auxiliary interference optical signal and acquire the reference state main path interference optical signal, the measurement state main path interference optical signal, the reference state wavelength monitoring signal and the measurement state wavelength monitoring signal synchronously with the acquired reference state auxiliary interference optical signal and the measurement state auxiliary interference optical signal as an acquisition clock.

25. The fiber distributed physical quantity measuring apparatus based on laser tuning control according to claim 23 or 24, wherein: synchronously acquiring the reference state main path interference optical signal, the reference state auxiliary interference optical signal and the reference state wavelength monitoring signal; estimating the phase of the collected reference state wavelength monitoring signal according to the collected reference state auxiliary interference optical signal, and thereby performing nonlinear correction on the collected reference state main path interference optical signal and the reference state wavelength monitoring signal so that the reference state main path interference optical signal and the reference state wavelength monitoring signal have equal optical frequency intervals; and

synchronously acquiring the main path interference optical signal, the auxiliary interference optical signal and the wavelength monitoring signal in the measurement state; estimating the phase of the collected measurement state wavelength monitoring signal according to the collected measurement state auxiliary interference optical signal, and thereby performing nonlinear correction on the collected measurement state main path interference optical signal and the measurement state wavelength monitoring signal so that the measurement state main path interference optical signal and the measurement state wavelength monitoring signal have equal optical frequency intervals.

26. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 25, wherein: the non-linear correction includes resampling.

27. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 26, wherein: and the auxiliary interferometer unit is adopted and combined with a photoelectric phase-locked loop to realize the nonlinear correction of the main path interferometer and the laser output in the reference state and the measurement state.

28. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the main path interferometer unit includes a fiber interferometer having a Mach-Zehnder structure or a Michael grandchild structure.

29. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 23, wherein: the auxiliary interferometer unit comprises an optical fiber interferometer with a Mach-Zehnder structure or a Michael grandson structure.

30. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the wavelength monitoring unit comprises a gas chamber for outputting characteristic signals or a fiber grating with known central wavelength, or a spectrometer or a wavelength meter capable of directly obtaining wavelength, or a fiber interferometer or an FP standard or an optical resonant cavity, or a combination of the above.

31. The fiber optic distributed physical quantity measuring device based on laser tuning control of claim 14, wherein: the distributed feedback array laser comprises a plurality of laser diodes with fixed wavelength intervals and a multimode interference coupler, and different laser diodes are switched and output by electrical means.

32. An optical fiber distributed physical quantity measuring system based on laser tuning control to measure physical quantity change of an object to be measured, the system comprising: the optical fiber sensor is coupled to the object to be measured; a distributed feedback array laser configured such that selected ones of the distributed feedback array lasers provide output power stabilized laser output that continuously covers the entire selected laser diode's output wavelength range by changing their operating temperature such that they emit laser output having an overlapping wavelength range with adjacent ones of the selected laser diodes; a wavelength monitoring unit configured to receive the laser output to provide a wavelength monitoring signal containing absolute wavelength information of the laser output; a main path interferometer unit configured to receive the laser output and the reflected light of the optical fiber sensor and to cause the two to interfere to form a main path interference light signal; the acquisition unit is configured to synchronously acquire the main path interference optical signal and the wavelength monitoring signal in a measurement state including the physical quantity change to obtain a main path interference optical signal and a measurement state wavelength monitoring signal in the measurement state; the data processing unit is configured to determine splicing points in the acquired main path interference optical signal in the measurement state according to the received absolute wavelength information provided by the wavelength monitoring signal in the measurement state; removing the part except the splicing point in the wavelength overlapping region in the collected main path interference optical signal in the measurement state to form a spliced main path interference optical signal in the measurement state; and calculating the physical quantity change based on the main path interference optical signal, the spliced measuring state main path interference optical signal and the spliced reference state main path interference optical signal.

33. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the spliced reference state main path interference optical signal is pre-stored or obtained in real time in the following mode: the acquisition unit is configured to synchronously acquire the main-state interference optical signal and the wavelength monitoring signal in the reference state to form a reference-state main-state interference optical signal and a reference-state wavelength monitoring signal; the data processing unit is configured to determine a splicing point in the acquired reference state main path interference optical signal according to absolute wavelength information provided by the received reference state wavelength monitoring signal; and removing the part except the splicing point in the wavelength overlapping region in the collected reference state main path interference optical signal to form a spliced reference state main path interference optical signal.

34. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the device also comprises a storage unit which is used for storing the signal splicing position obtained by the data processing unit, storing the distributed physical quantity resolving result or directly storing the original acquisition signal so as to facilitate later off-line processing.

35. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the optical fiber sensor is configured on the measuring arm of the main path interferometer unit and is a common single mode optical fiber, or an optical fiber with a writing of a weak reflection optical fiber grating array with an isocentric wavelength, or an optical fiber with enhanced Rayleigh scattering.

36. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the distributed feedback array laser is configured to: each of the selected laser diodes has a starting wavelength tuned at the operating temperature that is less than an ending wavelength of a laser diode adjacent to the laser diode having a larger wavelength value tuned at the operating temperature such that output signals of adjacent wavelength laser diodes partially overlap spectrally.

37. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: also included is a temperature control unit configured to provide an operating temperature control signal to the distributed feedback array laser to cause the selected laser diode to output the reference state laser output and the measurement state laser output.

38. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the laser driver further comprises a drive current control unit configured to provide a constant drive current control signal to the laser diodes in the distributed feedback array laser such that each laser diode operates at a constant drive current.

39. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the method also comprises a laser diode selection unit: configured to switch a laser diode providing a laser output among the selected laser diodes.

40. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 39, wherein: the selected unit of the laser diode is an electrical switch.

41. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: further comprising an auxiliary interferometer unit configured to generate a reference state auxiliary interference light signal based on the received reference state laser output and a measurement state auxiliary interference light signal based on the received measurement state laser output.

42. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 41, wherein: the acquisition unit is configured to acquire the reference state auxiliary interference optical signal and the measurement state auxiliary interference optical signal and acquire the reference state main path interference optical signal, the measurement state main path interference optical signal, the reference state wavelength monitoring signal and the measurement state wavelength monitoring signal synchronously with the acquired reference state auxiliary interference optical signal and the measurement state auxiliary interference optical signal as an acquisition clock.

43. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 41, wherein: synchronously acquiring the reference state main path interference optical signal, the reference state auxiliary interference optical signal and the reference state wavelength monitoring signal; estimating the phase of the collected reference state wavelength monitoring signal according to the collected reference state auxiliary interference optical signal, and thereby performing nonlinear correction on the collected reference state main path interference optical signal and the reference state wavelength monitoring signal so that the reference state main path interference optical signal and the reference state wavelength monitoring signal have equal optical frequency intervals; and

synchronously acquiring the main path interference optical signal, the auxiliary interference optical signal and the wavelength monitoring signal in the measurement state; estimating the phase of the collected measurement state wavelength monitoring signal according to the collected measurement state auxiliary interference optical signal, and thereby performing nonlinear correction on the collected measurement state main path interference optical signal and the measurement state wavelength monitoring signal so that the measurement state main path interference optical signal and the measurement state wavelength monitoring signal have equal optical frequency intervals.

44. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 43, wherein: the non-linear correction includes resampling.

45. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 41, wherein: and the auxiliary interferometer unit is adopted and combined with a photoelectric phase-locked loop to realize the nonlinear correction of the main path interferometer and the laser output in the reference state and the measurement state.

46. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the main path interferometer unit includes a fiber interferometer having a Mach-Zehnder structure or a Michael grandchild structure.

47. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 41, wherein: the auxiliary interferometer unit comprises an optical fiber interferometer with a Mach-Zehnder structure or a Michael grandson structure.

48. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the wavelength monitoring unit comprises a gas chamber for outputting characteristic signals or a fiber grating with known central wavelength, or a spectrometer or a wavelength meter capable of directly obtaining wavelength, or a fiber interferometer or an FP standard or an optical resonant cavity, or a combination of the above.

49. The fiber optic distributed physical quantity measurement system based on laser tuning control of claim 32, wherein: the distributed feedback array laser comprises a plurality of laser diodes with fixed wavelength intervals and a multimode interference coupler, and different laser diodes are switched and output by electrical means.

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